Write a 3D matrix in latex with equation environment

Question

I am trying to write a 3D matrix in latex, that is of the following form:

I have checked few answers in this forum but they don't tell how to include the equation in the tickpicture environment. Moreover, the shape is not really what I am looking for.

Answer 1

This solution requires two steps: (1) the construction of the two matrices and (2) the layout of the matrices and the drawing of the lines.

For the first step I used the package nicematrix. For the second step a tikzpicture.

For convenience I defined two commands with the arrays to be able to change them without interfering with the tikz layout.

\documentclass[12pt,a4paper]{article}
\usepackage{nicematrix}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\newcommand{\matrixA}{% 
$\begin{bNiceMatrix}
a_{11}^{1}  &a_{12}^{1} & \Cdots        &a_{1m}^{1}\
\Vdots      &\Ddots     &               & \
            &           &               &\
a_{nm}^{1}  &           &               & a_{nm}^{1}\
    \end{bNiceMatrix}$
}
\newcommand{\matrixB}{% 
    $\begin{bNiceMatrix}
    a_{11}^{m}  &a_{12}^{m} & \Cdots        &a_{1m}^{m}\
    \Vdots      &\Ddots     &               & \
    &           &                           &\
    a_{nm}^{m}  &           &               & a_{nm}^{m}\
    \end{bNiceMatrix}$
}
\begin{tikzpicture}
    \node[inner sep=0pt] (matA) {\matrixA};
    \node[inner sep=0pt, above right = 10pt and 10pt of matA, scale=0.8] (matB) {\matrixB};
    \node[left= 0pt of matA] {$A=$};
    \draw[blue,shorten >=3mm, shorten <=4mm, dotted] (matA.north west)-- (matB.north west);
    \draw[blue,shorten >=3mm, shorten <=2mm, dotted] (matA.north east)-- (matB.north east);
    \draw[blue,shorten >=3mm, shorten <=2mm, dotted] (matA.south east)-- (matB.south east);
\end{tikzpicture}
\end{document}